Thermostatic indicator for electric fuses



Jan, 23,

F. 3. LA MAR.

THERMGSTAHG WDiCA R FOR ELECTRIC F1) FILED JUNE 7. 1920,

A TTORN E Y.

.T 0 all whom itmay concern;

Patented Ian. 23, 1923.

UNITED STATES PATENT OFFICE,

FRANK 0. LA MAB, OF PITTSBT J'RGH, PENNSYLVANIA.

THEBMOSTATIC INDICATOR FOR ELECTBIC FUSES.

Application filed June 7, 1920. Serial N0. 887,018. I

such fuses with an indicating device or at-.

' tachment, which is simple and economical in construction, and alsoeflicient and positive in operation, and the purpose of which is .to

positivelynotify an operator or attendant whether the circuit in whichthe fuse is placed as a protecting medium is open or closed, 'andthereby avoid all danger. of in-v jury to the operator or-attendant fromelectric shock in attempting torepair or adjust the machinery operatedby the current passing through the fuse and also to notify the o eratoror attendant when the fuse is b own-out so the fuse may be removed .forrefilling or reloading without dan r of shock, and also-avoid loss oftime an delay in locating a particular fuse, which has blown-out orbecome ruptured inservice.

Another object of the invention is .to provide'an indicator for anelectric fuse which is permanent and continuous in operation and needsno repair or replacement of parts,

a difficulty which is common in the indicators now in use on some typesof electric fuses. So far as I as aware I am the first to rovide anindicator for electric fuses whlch constitutes a permanent attachmentfor the fuse and which will continuously indicate' positively the flowor interruption of' current through the circuit in which the fuse islaced. e

,l vith this understanding of the broad principle and purpose of theinvention, it will be stated that the invention is particularly designedfor use in connection with what are known as refillable fuses and isapplicable to any of the well known fuses of this type, and I have shownherein the indicator forming the subject of this invention applied to arefillable fuse of the construction and principle of that type describedand claimed in my co-pending application filed June 3, 1920. a

In an application for patent for indicators for electric fuses filedconcurrently herewith I have'shown a fuse of this general type includingan electrically operated indicator wherein the indicator mechanism iscon.-

trolled or operated by a solenoid or electromagnet connected in circuitwith the fuse element, and the object of this invention is to provide anelectrically operated thermo- -form of'the indicator involved in theprinciple of the invention.

The invention, therefore, consists in an electric fuse, comprising acasing, a fuse element fixed in said casing, and an electricallyoperated thermostatic indicator connected in circuit with thefuseelement, and also in the details of construction,combination andarrangement of parts, all substantially as'I will proceed now moreparticularly to set forth and finally claim. i v In the accompanyingdrawings, illustrating the invention, in the several views of which likeparts are similarly designated, Figure 1 is an elevation of the fuse.Fig. 2 is a longitudinal section of the fuse on a larger scale. Fig. 3is a transverse section, taken substantially in the plane of line 33,Fig. 2, and looking in the direction of the arrows, and Fig.4is apartial perspective view of the thermostatic indicator. In the drawings,1 is the casing, having an elongated opening 2 in its side. 3 and 4 areportions of a two-part plug member of suitable insulating or refractorymaterial adapted to be permanently orotherwise securely fastened uponthe inside of the casing about centrally thereof. These portions 3 and 4of the. plug are similar in construction and comprise solid block-likeend portions hav-- ing their outer faces beveled, and inwardlyprojecting, reduced and narrowed portions 5 and 6 at their inner facesadapted to abut at their ends when the parts are placed in the casing asherein shown, and serve' as a. supand 16, all substantially as in myapplicacat-0r which may be of any suitable con struction and arrangementto serve the .purpose ofthis invention. v

As herein shown the thermostat comprises two volute thermostatic members-18 fitted upon the projecting'portions 5 and 6 of the lug members 3 and4: and having their inner ends clamped upon the said. projectingportions 5 and 6 adj acent' to the inner faces of the plug members, bymeans of an insulating,

bar l9-and bolts 20 passing through the bar and projecting portions ofthe plug members? The outer free ends of the volute thermostatic members18 are connected by a narrowplate or bar 21, and the upper sur-' v faceof said plate or bar is provided with distinctively parallel coloredportions 22 and 23 such as blackand red, respectively, or any othermarks or characters to indicate on and oifff and when assembled inthefuse this plate or bar 21- will be adjacent to the opening 2 in thecasing and normally expose the black portion of the plate or bar.

-'l[he ends of-the bar or plate 21 project beyond the-volute thermostatsand extend into notches or cutaway rtions 24 at the edges of the innerfuses o the plug members, the ends 25 of said notches or cutawayportions servin as stops tov limit the movements of. the indicatingplate or bar in the operation of the device. 4

llhe inner; ends of the-volute thermostatic members 18 are connected incircuit with the main or fixed fuse elements 7 and 8 bymetallicconnections 26 clamped by the bar 19 or otherwise. heldincontact with the ends of thethermostats, and soldered or otherwiseelectrically cdnnected with the main or fixed fuse elements.

As in my concurrent application filed 7 herewith, the thermostaticelements and their from inijlury in case-of a blow out connectionswiththe 'mainrfuse elements will be of a Q greater load carrying ca citythan the main fuse elements, in or or toproteLct the thermostaticindicator overloa 'ng: thefifuse with removable end .ity than the'mainfuse-elements, as'has een clearly defined and for the' purpose as setforth in mysaid application. I,

.W'th, he fuse of theiprese'nt invention, it

is obvious that when inuse and the current turned on, the currentwillpass through the thermostatic elements .and cause them to cx .pand andby their torsional action will move the indicating bar 21 until the redportion indicate that the fuse has been blown.

lax or return to their normal position and a move the bar or plate 21 sothat its black portion will be exposed at the opening in the casing,thus indicating that the current is ofi. These operations are repeatedas many times asthe current traversing the fuse is turned on and off,thus making a permanent indicator for the ofi and on conditions of thecurrent passing through the fuse.

Should the fuse be blown by an excess current; the'removable end fuseswill be ruptured and the circuit broken thereby, and the thermostaticindicator be thrown out of circuit and the indicator bar returned tonormal position with its black portion exposed at the opening in thecasing to indicate that the fuse had been blown and requires new orfresh removable end fuse elements.

lln refilling the fuse, should it be reloaded withcnd fuse elements ofgreater carrying capacity than the main or permanently fixed fuseelement'and the current turned on and the. fuse subjected to an overloador short circuit, the main or fixed fuse element would be blownoutor-nuptured and open the circuit and permanently destroying the fuseagainst further use,'thu-'s causing the ther-. mostatic indicator" torelax and return the indicating bar-to bring its black portionoppositethe opening in the casing' andthus Thus, it will be observedthat I have provided a fuse which isabsolutely safe and protectiveagainst the possibility of overloading, which as is well known is theserious objection and dangerous element existing in fuses ofthis sortnow in common use. It do not wish to be understood as limiting thisinvention to the; specific details of construction herein shown-anddescribed, as the same may bealtered in various particulars, 1 and stillbe within the scope of the appended claims. What I claim is due to 1 1.an electric fuse, comprising a casing, a v

a fuse element fixed in said casing, and an fuse elements of greaterload carrying ca acelectrically operated-thermostatic indicatorconnected in circuit with said fuse element to indicate the off and onconditions of the Y current passing through said fuse.

12.;An electric fuse, coniprising a casing having ancpen ng therein, afuse element fixed in said casing,'and an electrically operatedthermostatic indicator located in the casing and connected in circuitwith the fuse element and adapted to indicate the off and plug, anelectrically operated thermostatic indicator fitted in the recess insaid plug and connected incircuit with the fuse element," whereby theindicator is'operated by the current passing through the fuse toindicate the off and on conditions of the current at the opening in thecasing.

4:. An electric fuse, comprising a casing having an opening therein, aplug of insulatmg material comprising two like or similar membersadapted to be fitted in the ends of the casing and having reducedinwardly projecting abutting portions adapted to form a recessvbetweenthe ends of the. plug, mainfuse elements carried by the plug members andhaving their terminals exposed at the outer ends thereof, anelectrically operated thermostatic indicator fitted in the recessbetween said plug members and supported therein by theinwardlyprojecting portions of said members and electrically connected with saidfuse elements, and removable fuse elements adapted to-be inserted in theends of the casing and contacting with the terminals of the main fuseelements, the said thermostatic. indicator adapted tobe operated by thecurrent passing through the fuse to indicate the off and on conditionsof the current at the opening in said casing. a

5. In an electric fuse, a casin having an opening therein, a fuseelement xed in said casing, and a thermostatically operated indicatingmechanism mounted in said casing and comprising two volute thermostaticmembers supported at their inner ends in spaced relation, and anindicating bar or plate connecting the outer ends of said thermostaticmembers and arranged adjacent to the opening in the casing, saidthermostatic members being connected in circuit with the fuse element,whereby said indicating bar or'plate will be moved with relation to theopening in the casing by the expansion and contraction of thethermostatic members when the current passing through the fuse is on andoff. A

In testimony whereof I' have hereunto set my name this 7th day of June,A] D. 1920.

FRANK 0. LA MAR.

